When shipping orders from your Magento 2 store, you may come across the following error:
There are a few reasons you may experience this issue, two of the most common are as follows:
1. When accessing Shiptheory the Shiptheory user may not have permissions or the correct level of permission. This can be done by updating the user (typically called shiptheory_0 through Magento 2) from "shiptheory" to "admin".
2. Secondly when updating your store from pre 2.4 you may encounter the above issue when pulling through new orders. This is often due to a reason with one of the changes from pre 2.4 to post 2.4. This can be found under your configuration tab and OAuth. The setting highlighted below should be set to "Yes" if it is not change this and hit save. Then try to reauthorise your store and see if this makes a change.